I am learning WaitGroup
from the blog https://nathanleclaire.com/blog/2014/02/15/how-to-wait-for-all-goroutines-to-finish-executing-before-continuing/
the code:
package main
import (
"fmt"
"sync"
"time"
)
func main() {
messages := make(chan int)
var wg sync.WaitGroup
// you can also add these one at
// a time if you need to
wg.Add(3)
go func() {
defer wg.Done()
time.Sleep(time.Second * 3)
messages <- 1
}()
go func() {
defer wg.Done()
time.Sleep(time.Second * 2)
messages <- 2
}()
go func() {
defer wg.Done()
time.Sleep(time.Second * 1)
messages <- 3
}()
go func() {
for i := range messages {
fmt.Println(i)
}
}()
wg.Wait()
}
I think it should print 3, 2 and 1 in order. But it only prints 3, 2 but 1 is missing, what's the problem?
You can tree it on https://play.golang.org/p/kZCvDhykYM